Image reproduction systems, such as printers and copiers, often include an image transfer device having an image transfer member, usually in the form of a belt or a drum, for receiving on its surface a marking substance, such as toner or ink, in image form and for subsequently transferring these images of marking substance in a transfer zone to a recording medium, such as paper. In an operative state, the image transfer member is urged against a counter member in the transfer zone while the recording medium passes therebetween. The transfer may take place by means of pressure, or heat, or heat and pressure each of them optionally being assisted by electrostatic forces and/or vibrational forces. Particularly in case the marking substance is a toner, the marking substance must be fixed onto the receiving material in order to render the images permanent. By applying an appropriate amount of pressure and heat in the transfer zone, transfer and fixing take place simultaneously. Otherwise a subsequent fixing step must be executed. For example, this may be done by feeding the recording medium, onto which the unfixed marking substance is already deposited, through a fixing zone where an increased temperature and pressure serve to fix the image permanently to the recording medium.
In such image transfer devices, contaminants, e.g., in the form of residual marking substance material and/or debris originating from the recording medium and/or other impurities may build up on the surface of the image transfer member. For instance, when the recording medium is paper or a like fibrous material, debris in the form of dust and fibers may build up on the image transfer member surface in the region of the transfer zone. If these contaminants remain on the image transfer member surface, the efficiency of the image transfer and the quality of the fixing, where applicable, may be affected. Hence, it is desirable to clean the surface of the image transfer member.
It is known to provide an endless cleaning member having a tacky substance on its surface and being positioned downstream of the transfer zone for removing contaminants from the image transfer member surface when being engaged in contact therewith. It is also known that over time, the tackiness of the cleaning member is reduced and hence the surface layer of the cleaning member needs to be rejuvenated. As disclosed in U.S. Pat. No. 4,705,388 (Huntjens et al./Océ-Nederland BV) or EP 0994861 (Douvdevani et al./Indigo N.V.), this may, for instance, be done by periodically developing a non-image pattern of a tacky substance, in casu toner, on an image transfer member to rejuvenate the surface layer of the cleaning member. In such a rejuvenation state, the image transfer member with the non-image toner pattern thereon passes the transfer zone while no recording medium is supplied and without urging the counter member against the image transfer member. The non-image toner pattern on the image transfer member is guided further towards the contact zone between the image transfer member and the cleaning member, i.e. the cleaning zone. When the image transfer member with the non-image toner pattern passes the cleaning zone, the non-image toner pattern is transferred to the cleaning member surface thereby rejuvenating it. The periodic rejuvenation of the tacky surface layer as described is found to lead to inconsistent cleaning characteristics caused by the reduction of the surface tackiness when proceeding in the operative state towards the next rejuvenation period. From this perspective, it seems beneficial to implement a high rejuvenation periodicity. However, contrary to the operative state, in the rejuvenation stage no prints or copies are generated and thus a high rejuvenation period is detrimental for the productivity of the image reproduction device. These conflicting requirements demand for a new approach for rejuvenating the tacky surface of the cleaning member.